1 /* -*- mode: c; c-basic-offset: 8; -*- 2 * vim: noexpandtab sw=8 ts=8 sts=0: 3 * 4 * inode.c - basic inode and dentry operations. 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public 8 * License as published by the Free Software Foundation; either 9 * version 2 of the License, or (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 * General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public 17 * License along with this program; if not, write to the 18 * Free Software Foundation, Inc., 59 Temple Place - Suite 330, 19 * Boston, MA 021110-1307, USA. 20 * 21 * Based on sysfs: 22 * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel 23 * 24 * configfs Copyright (C) 2005 Oracle. All rights reserved. 25 * 26 * Please see Documentation/filesystems/configfs.txt for more information. 27 */ 28 29 #undef DEBUG 30 31 #include <linux/pagemap.h> 32 #include <linux/namei.h> 33 #include <linux/backing-dev.h> 34 #include <linux/capability.h> 35 #include <linux/sched.h> 36 #include <linux/lockdep.h> 37 #include <linux/slab.h> 38 39 #include <linux/configfs.h> 40 #include "configfs_internal.h" 41 42 #ifdef CONFIG_LOCKDEP 43 static struct lock_class_key default_group_class[MAX_LOCK_DEPTH]; 44 #endif 45 46 extern struct super_block * configfs_sb; 47 48 static const struct address_space_operations configfs_aops = { 49 .readpage = simple_readpage, 50 .write_begin = simple_write_begin, 51 .write_end = simple_write_end, 52 }; 53 54 static struct backing_dev_info configfs_backing_dev_info = { 55 .name = "configfs", 56 .ra_pages = 0, /* No readahead */ 57 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, 58 }; 59 60 static const struct inode_operations configfs_inode_operations ={ 61 .setattr = configfs_setattr, 62 }; 63 64 int configfs_setattr(struct dentry * dentry, struct iattr * iattr) 65 { 66 struct inode * inode = dentry->d_inode; 67 struct configfs_dirent * sd = dentry->d_fsdata; 68 struct iattr * sd_iattr; 69 unsigned int ia_valid = iattr->ia_valid; 70 int error; 71 72 if (!sd) 73 return -EINVAL; 74 75 sd_iattr = sd->s_iattr; 76 77 error = inode_change_ok(inode, iattr); 78 if (error) 79 return error; 80 81 error = inode_setattr(inode, iattr); 82 if (error) 83 return error; 84 85 if (!sd_iattr) { 86 /* setting attributes for the first time, allocate now */ 87 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL); 88 if (!sd_iattr) 89 return -ENOMEM; 90 /* assign default attributes */ 91 sd_iattr->ia_mode = sd->s_mode; 92 sd_iattr->ia_uid = 0; 93 sd_iattr->ia_gid = 0; 94 sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME; 95 sd->s_iattr = sd_iattr; 96 } 97 98 /* attributes were changed atleast once in past */ 99 100 if (ia_valid & ATTR_UID) 101 sd_iattr->ia_uid = iattr->ia_uid; 102 if (ia_valid & ATTR_GID) 103 sd_iattr->ia_gid = iattr->ia_gid; 104 if (ia_valid & ATTR_ATIME) 105 sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime, 106 inode->i_sb->s_time_gran); 107 if (ia_valid & ATTR_MTIME) 108 sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime, 109 inode->i_sb->s_time_gran); 110 if (ia_valid & ATTR_CTIME) 111 sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime, 112 inode->i_sb->s_time_gran); 113 if (ia_valid & ATTR_MODE) { 114 umode_t mode = iattr->ia_mode; 115 116 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID)) 117 mode &= ~S_ISGID; 118 sd_iattr->ia_mode = sd->s_mode = mode; 119 } 120 121 return error; 122 } 123 124 static inline void set_default_inode_attr(struct inode * inode, mode_t mode) 125 { 126 inode->i_mode = mode; 127 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 128 } 129 130 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr) 131 { 132 inode->i_mode = iattr->ia_mode; 133 inode->i_uid = iattr->ia_uid; 134 inode->i_gid = iattr->ia_gid; 135 inode->i_atime = iattr->ia_atime; 136 inode->i_mtime = iattr->ia_mtime; 137 inode->i_ctime = iattr->ia_ctime; 138 } 139 140 struct inode * configfs_new_inode(mode_t mode, struct configfs_dirent * sd) 141 { 142 struct inode * inode = new_inode(configfs_sb); 143 if (inode) { 144 inode->i_mapping->a_ops = &configfs_aops; 145 inode->i_mapping->backing_dev_info = &configfs_backing_dev_info; 146 inode->i_op = &configfs_inode_operations; 147 148 if (sd->s_iattr) { 149 /* sysfs_dirent has non-default attributes 150 * get them for the new inode from persistent copy 151 * in sysfs_dirent 152 */ 153 set_inode_attr(inode, sd->s_iattr); 154 } else 155 set_default_inode_attr(inode, mode); 156 } 157 return inode; 158 } 159 160 #ifdef CONFIG_LOCKDEP 161 162 static void configfs_set_inode_lock_class(struct configfs_dirent *sd, 163 struct inode *inode) 164 { 165 int depth = sd->s_depth; 166 167 if (depth > 0) { 168 if (depth <= ARRAY_SIZE(default_group_class)) { 169 lockdep_set_class(&inode->i_mutex, 170 &default_group_class[depth - 1]); 171 } else { 172 /* 173 * In practice the maximum level of locking depth is 174 * already reached. Just inform about possible reasons. 175 */ 176 printk(KERN_INFO "configfs: Too many levels of inodes" 177 " for the locking correctness validator.\n"); 178 printk(KERN_INFO "Spurious warnings may appear.\n"); 179 } 180 } 181 } 182 183 #else /* CONFIG_LOCKDEP */ 184 185 static void configfs_set_inode_lock_class(struct configfs_dirent *sd, 186 struct inode *inode) 187 { 188 } 189 190 #endif /* CONFIG_LOCKDEP */ 191 192 int configfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *)) 193 { 194 int error = 0; 195 struct inode * inode = NULL; 196 if (dentry) { 197 if (!dentry->d_inode) { 198 struct configfs_dirent *sd = dentry->d_fsdata; 199 if ((inode = configfs_new_inode(mode, sd))) { 200 if (dentry->d_parent && dentry->d_parent->d_inode) { 201 struct inode *p_inode = dentry->d_parent->d_inode; 202 p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME; 203 } 204 configfs_set_inode_lock_class(sd, inode); 205 goto Proceed; 206 } 207 else 208 error = -ENOMEM; 209 } else 210 error = -EEXIST; 211 } else 212 error = -ENOENT; 213 goto Done; 214 215 Proceed: 216 if (init) 217 error = init(inode); 218 if (!error) { 219 d_instantiate(dentry, inode); 220 if (S_ISDIR(mode) || S_ISLNK(mode)) 221 dget(dentry); /* pin link and directory dentries in core */ 222 } else 223 iput(inode); 224 Done: 225 return error; 226 } 227 228 /* 229 * Get the name for corresponding element represented by the given configfs_dirent 230 */ 231 const unsigned char * configfs_get_name(struct configfs_dirent *sd) 232 { 233 struct configfs_attribute *attr; 234 235 BUG_ON(!sd || !sd->s_element); 236 237 /* These always have a dentry, so use that */ 238 if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK)) 239 return sd->s_dentry->d_name.name; 240 241 if (sd->s_type & CONFIGFS_ITEM_ATTR) { 242 attr = sd->s_element; 243 return attr->ca_name; 244 } 245 return NULL; 246 } 247 248 249 /* 250 * Unhashes the dentry corresponding to given configfs_dirent 251 * Called with parent inode's i_mutex held. 252 */ 253 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent) 254 { 255 struct dentry * dentry = sd->s_dentry; 256 257 if (dentry) { 258 spin_lock(&dcache_lock); 259 spin_lock(&dentry->d_lock); 260 if (!(d_unhashed(dentry) && dentry->d_inode)) { 261 dget_locked(dentry); 262 __d_drop(dentry); 263 spin_unlock(&dentry->d_lock); 264 spin_unlock(&dcache_lock); 265 simple_unlink(parent->d_inode, dentry); 266 } else { 267 spin_unlock(&dentry->d_lock); 268 spin_unlock(&dcache_lock); 269 } 270 } 271 } 272 273 void configfs_hash_and_remove(struct dentry * dir, const char * name) 274 { 275 struct configfs_dirent * sd; 276 struct configfs_dirent * parent_sd = dir->d_fsdata; 277 278 if (dir->d_inode == NULL) 279 /* no inode means this hasn't been made visible yet */ 280 return; 281 282 mutex_lock(&dir->d_inode->i_mutex); 283 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) { 284 if (!sd->s_element) 285 continue; 286 if (!strcmp(configfs_get_name(sd), name)) { 287 spin_lock(&configfs_dirent_lock); 288 list_del_init(&sd->s_sibling); 289 spin_unlock(&configfs_dirent_lock); 290 configfs_drop_dentry(sd, dir); 291 configfs_put(sd); 292 break; 293 } 294 } 295 mutex_unlock(&dir->d_inode->i_mutex); 296 } 297 298 int __init configfs_inode_init(void) 299 { 300 return bdi_init(&configfs_backing_dev_info); 301 } 302 303 void __exit configfs_inode_exit(void) 304 { 305 bdi_destroy(&configfs_backing_dev_info); 306 } 307